P0171 and P0174 lean codes

[atikovi]

Just got this 2000 LS V6 and it has those two codes with the CEL on. Would that be a vacuum leak related? I can hear air hissing from under the dash when idling. The hissing goes away when I step on the gas, I guess because vacuum drops under power. Also the engine takes a few seconds to idle down when coming to a stop. It will hang at like 1600 rpm for 2-3 seconds before dropping down to normal. (5-speed) Any suggestions before I smoke it?

 

[Chinden]

I am having the same problem. p0174 with random misfires did all new plugs coils egr pcv valve and elbow coming to think it is iac or tps. I hear air hissing from egr but everything seems tight about to test it soon.

 

[Maverick74]

Try to chase down any vacuum leaks. Can clean the MAF sensor and see if that helps. There are videos on you tube that explain that. I always try to hold it that the spray does not run into the sensor.. your just trying to clean the heated wire.

 

[tireman]

I have the V6, this is a vacuum leak after the throttle body. The leak is most likely the elbow to PCV. The vacuum goes from the throttle body to the back of the engine with a solid plastic line. Follow it to the rear of the engine. Check the boot. They tear and split open. Other wise its the PCV elbow. Check all other vacuum hoses, but these are the usual problems.

 

[fudge12]

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[fudge12]

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